Problem: If $x \circledcirc y = x-4y$ and $x \oplus y = (6-x)(y)$, find $5 \oplus (5 \circledcirc 0)$.
Solution: First, find $5 \circledcirc 0$ $ 5 \circledcirc 0 = 5-(4)(0)$ $ \hphantom{5 \circledcirc 0} = 5$ Now, find $5 \oplus 5$ $ 5 \oplus 5 = (6-5)(5)$ $ \hphantom{5 \oplus 5} = 5$.